1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Management Component Transport Protocol (MCTP) 4 * 5 * Copyright (c) 2021 Code Construct 6 * Copyright (c) 2021 Google 7 */ 8 9 #ifndef __NET_MCTP_H 10 #define __NET_MCTP_H 11 12 #include <linux/bits.h> 13 #include <linux/mctp.h> 14 #include <linux/netdevice.h> 15 #include <net/net_namespace.h> 16 #include <net/sock.h> 17 18 /* MCTP packet definitions */ 19 struct mctp_hdr { 20 u8 ver; 21 u8 dest; 22 u8 src; 23 u8 flags_seq_tag; 24 }; 25 26 #define MCTP_VER_MIN 1 27 #define MCTP_VER_MAX 1 28 29 /* Definitions for flags_seq_tag field */ 30 #define MCTP_HDR_FLAG_SOM BIT(7) 31 #define MCTP_HDR_FLAG_EOM BIT(6) 32 #define MCTP_HDR_FLAG_TO BIT(3) 33 #define MCTP_HDR_FLAGS GENMASK(5, 3) 34 #define MCTP_HDR_SEQ_SHIFT 4 35 #define MCTP_HDR_SEQ_MASK GENMASK(1, 0) 36 #define MCTP_HDR_TAG_SHIFT 0 37 #define MCTP_HDR_TAG_MASK GENMASK(2, 0) 38 39 #define MCTP_HEADER_MAXLEN 4 40 41 #define MCTP_INITIAL_DEFAULT_NET 1 42 43 static inline bool mctp_address_ok(mctp_eid_t eid) 44 { 45 return eid >= 8 && eid < 255; 46 } 47 48 static inline struct mctp_hdr *mctp_hdr(struct sk_buff *skb) 49 { 50 return (struct mctp_hdr *)skb_network_header(skb); 51 } 52 53 /* socket implementation */ 54 struct mctp_sock { 55 struct sock sk; 56 57 /* bind() params */ 58 unsigned int bind_net; 59 mctp_eid_t bind_addr; 60 __u8 bind_type; 61 62 /* sendmsg()/recvmsg() uses struct sockaddr_mctp_ext */ 63 bool addr_ext; 64 65 /* list of mctp_sk_key, for incoming tag lookup. updates protected 66 * by sk->net->keys_lock 67 */ 68 struct hlist_head keys; 69 70 /* mechanism for expiring allocated keys; will release an allocated 71 * tag, and any netdev state for a request/response pairing 72 */ 73 struct timer_list key_expiry; 74 }; 75 76 /* Key for matching incoming packets to sockets or reassembly contexts. 77 * Packets are matched on (src,dest,tag). 78 * 79 * Lifetime / locking requirements: 80 * 81 * - individual key data (ie, the struct itself) is protected by key->lock; 82 * changes must be made with that lock held. 83 * 84 * - the lookup fields: peer_addr, local_addr and tag are set before the 85 * key is added to lookup lists, and never updated. 86 * 87 * - A ref to the key must be held (throuh key->refs) if a pointer to the 88 * key is to be accessed after key->lock is released. 89 * 90 * - a mctp_sk_key contains a reference to a struct sock; this is valid 91 * for the life of the key. On sock destruction (through unhash), the key is 92 * removed from lists (see below), and marked invalid. 93 * 94 * - these mctp_sk_keys appear on two lists: 95 * 1) the struct mctp_sock->keys list 96 * 2) the struct netns_mctp->keys list 97 * 98 * presences on these lists requires a (single) refcount to be held; both 99 * lists are updated as a single operation. 100 * 101 * Updates and lookups in either list are performed under the 102 * netns_mctp->keys lock. Lookup functions will need to lock the key and 103 * take a reference before unlocking the keys_lock. Consequently, the list's 104 * keys_lock *cannot* be acquired with the individual key->lock held. 105 * 106 * - a key may have a sk_buff attached as part of an in-progress message 107 * reassembly (->reasm_head). The reasm data is protected by the individual 108 * key->lock. 109 * 110 * - there are two destruction paths for a mctp_sk_key: 111 * 112 * - through socket unhash (see mctp_sk_unhash). This performs the list 113 * removal under keys_lock. 114 * 115 * - where a key is established to receive a reply message: after receiving 116 * the (complete) reply, or during reassembly errors. Here, we clean up 117 * the reassembly context (marking reasm_dead, to prevent another from 118 * starting), and remove the socket from the netns & socket lists. 119 * 120 * - through an expiry timeout, on a per-socket timer 121 */ 122 struct mctp_sk_key { 123 mctp_eid_t peer_addr; 124 mctp_eid_t local_addr; 125 __u8 tag; /* incoming tag match; invert TO for local */ 126 127 /* we hold a ref to sk when set */ 128 struct sock *sk; 129 130 /* routing lookup list */ 131 struct hlist_node hlist; 132 133 /* per-socket list */ 134 struct hlist_node sklist; 135 136 /* lock protects against concurrent updates to the reassembly and 137 * expiry data below. 138 */ 139 spinlock_t lock; 140 141 /* Keys are referenced during the output path, which may sleep */ 142 refcount_t refs; 143 144 /* incoming fragment reassembly context */ 145 struct sk_buff *reasm_head; 146 struct sk_buff **reasm_tailp; 147 bool reasm_dead; 148 u8 last_seq; 149 150 /* key validity */ 151 bool valid; 152 153 /* expiry timeout; valid (above) cleared on expiry */ 154 unsigned long expiry; 155 156 /* free to use for device flow state tracking. Initialised to 157 * zero on initial key creation 158 */ 159 unsigned long dev_flow_state; 160 struct mctp_dev *dev; 161 }; 162 163 struct mctp_skb_cb { 164 unsigned int magic; 165 unsigned int net; 166 int ifindex; /* extended/direct addressing if set */ 167 mctp_eid_t src; 168 unsigned char halen; 169 unsigned char haddr[MAX_ADDR_LEN]; 170 }; 171 172 /* skb control-block accessors with a little extra debugging for initial 173 * development. 174 * 175 * TODO: remove checks & mctp_skb_cb->magic; replace callers of __mctp_cb 176 * with mctp_cb(). 177 * 178 * __mctp_cb() is only for the initial ingress code; we should see ->magic set 179 * at all times after this. 180 */ 181 static inline struct mctp_skb_cb *__mctp_cb(struct sk_buff *skb) 182 { 183 struct mctp_skb_cb *cb = (void *)skb->cb; 184 185 cb->magic = 0x4d435450; 186 return cb; 187 } 188 189 static inline struct mctp_skb_cb *mctp_cb(struct sk_buff *skb) 190 { 191 struct mctp_skb_cb *cb = (void *)skb->cb; 192 193 BUILD_BUG_ON(sizeof(struct mctp_skb_cb) > sizeof(skb->cb)); 194 WARN_ON(cb->magic != 0x4d435450); 195 return (void *)(skb->cb); 196 } 197 198 /* If CONFIG_MCTP_FLOWS, we may add one of these as a SKB extension, 199 * indicating the flow to the device driver. 200 */ 201 struct mctp_flow { 202 struct mctp_sk_key *key; 203 }; 204 205 /* Route definition. 206 * 207 * These are held in the pernet->mctp.routes list, with RCU protection for 208 * removed routes. We hold a reference to the netdev; routes need to be 209 * dropped on NETDEV_UNREGISTER events. 210 * 211 * Updates to the route table are performed under rtnl; all reads under RCU, 212 * so routes cannot be referenced over a RCU grace period. Specifically: A 213 * caller cannot block between mctp_route_lookup and mctp_route_release() 214 */ 215 struct mctp_route { 216 mctp_eid_t min, max; 217 218 struct mctp_dev *dev; 219 unsigned int mtu; 220 unsigned char type; 221 int (*output)(struct mctp_route *route, 222 struct sk_buff *skb); 223 224 struct list_head list; 225 refcount_t refs; 226 struct rcu_head rcu; 227 }; 228 229 /* route interfaces */ 230 struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet, 231 mctp_eid_t daddr); 232 233 int mctp_local_output(struct sock *sk, struct mctp_route *rt, 234 struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag); 235 236 void mctp_key_unref(struct mctp_sk_key *key); 237 238 /* routing <--> device interface */ 239 unsigned int mctp_default_net(struct net *net); 240 int mctp_default_net_set(struct net *net, unsigned int index); 241 int mctp_route_add_local(struct mctp_dev *mdev, mctp_eid_t addr); 242 int mctp_route_remove_local(struct mctp_dev *mdev, mctp_eid_t addr); 243 void mctp_route_remove_dev(struct mctp_dev *mdev); 244 245 /* neighbour definitions */ 246 enum mctp_neigh_source { 247 MCTP_NEIGH_STATIC, 248 MCTP_NEIGH_DISCOVER, 249 }; 250 251 struct mctp_neigh { 252 struct mctp_dev *dev; 253 mctp_eid_t eid; 254 enum mctp_neigh_source source; 255 256 unsigned char ha[MAX_ADDR_LEN]; 257 258 struct list_head list; 259 struct rcu_head rcu; 260 }; 261 262 int mctp_neigh_init(void); 263 void mctp_neigh_exit(void); 264 265 // ret_hwaddr may be NULL, otherwise must have space for MAX_ADDR_LEN 266 int mctp_neigh_lookup(struct mctp_dev *dev, mctp_eid_t eid, 267 void *ret_hwaddr); 268 void mctp_neigh_remove_dev(struct mctp_dev *mdev); 269 270 int mctp_routes_init(void); 271 void mctp_routes_exit(void); 272 273 void mctp_device_init(void); 274 void mctp_device_exit(void); 275 276 #endif /* __NET_MCTP_H */ 277